Re: why so few cnc lathe conversions?

Hi Jeffe,

I did my 7x12.
http://www.wrathall.com/Interests/interests_index.htm

As others have said, a 360 Ozin stepper is a bit to wimpy for Z, but
will be fine on X. What Y axis? If you mean the compound, don't
bother, just remove it and make a nice rigid pedestal mount for the
tool post.

Do you have a full set of quick change tooling? Without this, you are
really slow as every tool change requires rezeroing.

Zero back lash ballscrews are the way to do it properly, but if you
can't fit a ball screw on X (differcult on the 7x12) then there is no
point on the Z. Most lathe cutting is in one direction, so backlash
is less of an issue than for a CNC mill.

Gearing the motors is not essential (if you get good strong motors)
but a 2:1 reduction with timing belts cost about the same as decent
couplings, but make alignment much easier if you don't have a mill.

I'd say:
700+ Ozin Z motor (100$ ebay)
360 Oz in X motor ($50 ebay)
2:1 reduction timing belts (~$100 for two sets)
2x Gecko 210's ($250) ( although you could use a 2.5A Xylotex for X
if you get a high inductance motor, but your PSU will then have to be
limited to about 30V)
350W 50VÀC toroid transformer ($70)
100V Bridge rectifier (~$10)
Capacitor (go to Geckodrive.com read the white paper on PSU's and
work out the exact size you need. Work be too big though. (~$35)
Old PC (~$20)
TurboCNC (~$20)
One/rev encoder (~$20)
Wiring, microswitchs, enclosure (anywhere from free to $1000
depending on how much time you have and how go a scrounger you are)
Access to a mill would make it easier to make the various brackets)

Go for it. It's fun, you already have the machine, and at the worst,
it will no worse than a manual machine where you have to take up
backlash on each cut.

Regards,
Mark



--- In CAD_CAM_EDM_DRO@yahoogroups.com, "jlsmith269"
<jlsmith269@y...> wrote:

> I am wondering why there are so few lathe conversions vs mills?
>
> I bought a frejoth 13x37 gearhead, with crashed threading gears...

the

> machine MIGHT have had 10 hours on it, before it was crashed.
>
> My plan it to stick some 360oz/in on the x, y, and y, and drive

this

> thing as a super tight lathe. The runout of the headstock is very
> small, and I think I can do this for
>
> 3x360 motors with encoders(250)
> xxx? drive (200)
> power supply , pc based? 50
> cables and wiring, 200?
> 700 bucks, before gearing?
>
> Speaking of gearing, do you guys make your own gear drives or buy
> them? If buy them, where?
>
> Jeffe